Lubricating oil additives



United States Patent O LUBRICATING 01L ADDITIVES William C. Hollyday,Jr., Fanwood, N. J., assignor to Esso Research and Engineering Company,a corporation of Delaware No Drawing. Application February 27, 1952,Serial No. 273,780

9 Claims. (Cl. 25%-51.5)

This invention relates to lubricating oil additive compositions and tomineral oil blends of such. additives. Particularly the inventionrelates to polyamides that are oil soluble and that modify the waxcrystals which form at low temperatures.

The lubricating oil art is familiar with the concept of increasing thelow temperature fluidity of mineral oils containing wax therein byincorporation of additive materials. These materials are known to theart as pour point depressors in that'they reduce the temperature atwhich the lubricating oil loses its property of free flow due toentrainment in a wax crystalline structure. The instant invention isdirected toward such pour point depressors. v

It has beenfound and forms the object of this invention that a new typeof pour point depressant may be formed by copolymeri'zing with a dibasicacid or anhydride a di-amine compound which in turn has been formed byreacting an amine with ethylenimine. So far as is known this is thefirst instance of the formation of these oil soluble polyamides.

It has been found that these materials when blended in lubricating oilsin proportions ranging from'0.001% to about 5.0% by weight materiallyreduce the pour point of the composition. Although blends containingthis range of additive material are successful it is preferred to useabout 0.01% to 0.5% by weight of the oil soluble polyamides of thisinvention.

The diamines are prepared by reacting ethylenimine with a long chainprimary aliphatic amine in accordance with the following equation:

1 RNHz+ 011 6111, RNCIhCIhNH:

Temperatures within the range of 150 C. to 225 C. are required for thisreaction and a range of 180 C. to 200 C. is preferred. The reaction maybe carried out in the presence of a solvent such as o-dichlorobenzene,xylene, tetralin, decalin, etc.

A Friedel-Crafts catalyst such as aluminum chloride is desired. Althoughit is preferred to use about .80 mol of catalyst per mol of amine, anoperable range of catalyst is 0.5 to 1.5. mols per mole of the amineused. The reaction takes from to 60 minutes to complete and under normalcircumstances will require from 10 to 30 minutes.

The major proportion of the oil solubility imparted to the resultingfinished composition is obtained through the length of the R group, thatis, the aliphatic portion of the primary amine. In the instant inventionR is an aliphatic radical containing from 8 to 18 carbon atoms of eitherslightly branched or straight chain configuration, the latter beingpreferred. If desired, mixtures of various of the aliphatic amines maybe employed. A series of aliphatic primary amines have recently becomecommercially available and are known to the trade as ARMEENS availablethrough Armour & Company.

2,744,071 Patented May 1, 1956 1/(RNHCHzCH NHz) 1 (HO O C--(CHz) r0 0OH) It is noted that one molecular amount of the amine is reacted withone mol of the dibasic acid or anhydridc. The resulting polyamide willhave a molecular weight from about 500 to 50,000 depending upon the timeand temperature of the reaction. In the preferred embodiment of thisinvention a molecular weight of from 1,000 to 20,000 is most desirable.The reaction should be carried out at a temperature within a range fromabout C. to 200 0., preferably -l50 C. The amidation reaction may becarired out in the presence of the solvent such as benzene, naphtha,toluene, xylene and the like. Ordinarily the reaction will continue forfrom 5 to 15 hours depending upon the starting materials used and willbe continued, at any event, until substantially the theoretical amountof water is evolved. A In the dibasic acid formula given in Equation II,x may be a number from 2 to 8, that is to say, the dibasic acid oranhydride will contain from about 4 to about 10 carbon atoms.

Operable dibasic acids include succinic, glutaric, adipic, pimelic,suberic, azelaic, sebacic, etc. Mixtures of the above acids may also beused.

The invention will be more clearly explained by reference to thefollowing examples:

EXAMPLE 1 To a flask fitted with a stirrer, dropping funnel, thermometerand condenser were charged 250 ml. of odichlorobenzene and 26.6 g. (0.20mole) of anhydrous aluminum chloride. The mixture was stirred topartially dissolve the aluminum chloride. To this mixture was then addedportion-wise 50 g. (0.25 mole) of a mixture of primary aliphatic aminesranging from C8 to Cm in composition and having an average molecularweight of 200. The aluminum chloride went into solution completely.

The resultant solution was heated to reflux C.) and 10.8 g. (0.25 mole)of ethylenimine was added drop-wise over 15 minutes. Reflux wasmaintained for about 45 minutes. At the end of this time the reactionmixture was cooled and thoroughly washed with 25% sodium hydroxidesolution.- The o-dichlorbenzene layer contained the alkyl substitutedethylene diamine.

The o-dichlorobenzene solution of alkyl ethylene diamine was dilutedwith 300 ml. of benzene and transferred to a flask fitted with astirrer, thermometer and separator for removing water from the condensedoverhead. Exactly 6.0 g. (0.05 mole) of succinic acid, 14.6 g. (0.10mole) of adipic acid and 10.0 g. (0.05 mole) of sebacic acid were added.The mixture was heated gently until the acids went into solution, andthen refluxed for 15 hours. During this time about 6 ml. (0.33 mole) ofwater collected and it is thought some water was probably lost alongwith benzene vapors.

At the end of this time the solvents were removed from the product bydistillation and by blowing with nitrogen. The residue was a viscous,brown, waxy material, weight 82 g. This product was tested as a pourdepressant in a Mild-Continent SAE 20 grade oil with the results givenin Ta 1e I.

3 EXAMPLE 2 This was similar to Example 1 except hexadecyl amine wasused in place of the mixture of amines, and sebacic was used in place ofthe mixture of dibasic acids.

EXAMPLE 3 This was similar to Example 2 except the molar ratio ofethylenimine to hexadecyl amine was 1.25 instead of 1.00.

EXAMPLES 4 TO 7 These were similar to Example 1 except for the reactantsused as noted in Table I.

Results obtained upon testing these materials as pour depressants aregiven in Table I.

Table I POLYAMIDES AS OIL ADDITIVES [Pour depressant action] Test oil: aconventionally refined Mid-Continent SAE 20 grade, pour point +10 F.

To summarize briefly this invention relates to pour point depressantsfor mineral lubricating oil which are formed by amidating a dibasic acidor its anhydride with a reaction product of ethylenimine and a primaryamine. The dibasic acid for best results will contain from 4 to 10carbon atoms and the aliphatic amine will contain from 8 to 18 carbonatoms per molecule. The materials are blended in lubricating oils inamounts from 0.005% to by weight based on the weight of the totalcomposition.

What is claimed is:

l. A lubricating oil composition having outstanding low temperatureproperties which comprises a major portion of a mineral lubricating oiland a pour point depressing amount of a polyamide, of suflicientmolecular weight to be oil soluble, of substantially equimolecularamounts of an amine constituent, selected from the group consisting ofdiamines having the general formula:

wherein R is an alkyl group containing from about 8 to 18 carbon atoms,and mixtures thereof, and an acid constituent selected from the groupconsisting of dibasic acids having the formula: HOOC(CH2)COOH wherein xis an integer from about 2 to 8, their anhydrides and mixtures thereof.

2. A lubricating oil composition according to claim 1, wherein saidpolyamide has a molecular weight of about 500 to 50,000.

3. A lubricating oil composition according to claim 1, wherein saidpolyamide has a molecular weight of about 1,000 to 20,000.

4. A lubricating oil composition according to claim 1, wherein saidamine constituent is a mixture of diamines in which R is an alkyl groupcontaining from about 8 to 18 carbon atoms, and said acid constituent isa mixture of dibasic acids wherein x of the formula is from about 2 to8.

5. A lubricating oil composition according to claim 1, wherein R is analkyl group containing 16 carbon atoms and said acid constituent issebacic acid.

6. A lubricating oil composition according to claim 1, wherein R is analkyl group containing 14 carbon atoms and said acid constituent issuccinic acid.

7. A lubricating oil composition according to claim 1, wherein R is analkyl group containing 16 carbon atoms and said acid constituent isadipic acid.

8. A lubricating oil composition according to claim 1, wherein R is analkyl group containing 18 carbon atoms and said acid constituent issebacic acid.

9. A lubricating oil composition according to claim 1, wherein saidamine constituent is a mixture of diamines in which R is an alkyl groupcontaining from about 14 to 18 carbon atoms and said acid constituent isa mixture of dibasic acids wherein x of the formula is from about 4 to10.

References Cited in the file of this patent UNITED STATES PATENTS2,293,388 Hanford Aug. 18, 1942 2,388,035 Frosch Oct. 30, 1945 2,435,631Lieber Feb. 10, 1948 2,594,286 Bryant ct al Apr. 29, 1952 2,604,451Rocchini July 22, 1952

1. A LUBRICATING OIL COMPOSITION HAVING OUTSTANDING LOW TEMPERATURE PROPERTIES WHICH COMPRISES A MAJOR PORTION OF A MINERAL LUBRICATING OIL AND A POUR POINT DEPRESSING AMOUNT OF A POLYAMIDE, OF SUFFICIENT MOLECULAR WEIGHT TO BE OIL SOLUBLE, OF SUBSTANTIALLY EQUIMOLECULAR AMOUNTS OF AN AMINE CONSTITUENT, SELECTED FROM THE GROUP CONSISTING OF DIAMINES HAVING THE GENERAL FORMULA: 